Main Drain Leak ?

[Janiemae]

Hi, I'm new to this forum. It seems there is a lot of good advice & I sure could use some. Our pool has been leaking for a few weeks. It leaks whether the pump is running or not. When the pump is running bubbles come out of the returns. It leaked below the skimmer level while running one night. We turned it off. It is now down another 2.5 inches.
We had a hole in the tubing, we replaced it and there seemed to be no more leaks above ground.
There is no leak around the filter, the filter basket, the backwash drain, none of that stuff.
My husband and I checked the skimmer and there are no cracks below water level. There is one at the concrete, but the water level leaks far below that.
Would a leak with the main drain cause bubbles from the return?
The water is still above the light, but would a leak there cause bubbles from the returns?
I think it's the main drain, but I'm not a pool expert.
We appreciate any help. Please.

 

[BoDarville]

Welcome to TFP! Sorry to hear about the leak.

Here are a couple of alternatives for determining if the main drain is leaking:

• 1. Make a batch of liquid sugar (sometimes called simple syrup). This video will show you how: http://www.youtube.com/watch?v=9CwLTpuciPE. The reason for making the simple syrup instead of using plain water is that the simple syrup is a little thicker. If you do have a leak at the main drain, the thicker mixture will be more apt to go down the drain in a more worm-like fashion. After making the simple syrup and placing it in a syringe or squeeze bottle, add some food coloring dye to it. Then go down to the main drain and release the mixture within 1/4 inch of the drain. If there is a leak in the drain plumbing, the dyed mixture should go down the drain as opposed to dispersing in the nearby water.
  
  2. If you have a test kit with the R-0011L reagent (used for CH testing) I have seen where a few members have used the R-0011L for dye testing.
  
  3. Dive down to the drain, remove the cover, and plug the opening. The leak could be anywhere between the drain and pump. You need to just stick a rubber plug or something similar in the pipe. Then leave it and do a bucket test (see Pool School - Leak Detection) and see if the leaking has stopped.